Regulation of developmental pathways by core transcription factors via their target genes in the EpiSC model. Regulation of developmental pathways by core transcription factors via their target genes in the EpiSC model. Some of these regulatory pathways have also been indicated by studies using ES cells: inhibition of Sox17 by Zic2/3 and activation of Zic3 by Sox2, Pou5f1 and Nanog (Lim et al., 2007), and the promotion of neural development by sustained high-level expression of Pou5f1 (Shimozaki et al., 2003). The function of Pou5f1 and Nanog in stabilizing the epiblastic state has been more clearly indicated in earlier studies (Mitsui et al., 2003; Vallier et al., 2009). Makiko Iwafuchi-Doi et al. Development 2012;139:3926-3937 © 2012.